Blavatsky
Original sense
The coiled fiery power at the base of the spine which, in the trained adept, rises through the centres and becomes a vehicle of higher knowledge. She treated premature awakening as a genuine cause of insanity and moral wreck. The Voice of the Silence uses the serpent as an image of this power, to be raised only under law.
Kundalini is the power that moves in a serpentine path… it is the world-mother, and for the unprepared it is death.
She preferred raja-yoga and inner ethics to hatha techniques designed to force the fire. Public instruction in raising kundalini she regarded as a betrayal of the school.